On Monday, Nature Water published a study by two NASA Goddard Space Flight Center scientists concluding the "strong" link between the global mean surface temperature and water-related extreme weather led the increase in the severity of events like floods and droughts in the past two decades.
Authors Matthew Rodell and Bailing Li wrote results suggest "rising temperatures may be driving an increase in the total intensity and related metrics of hydroclimatic extreme events that cannot be attributed to the sporadic occurrence of" regular climactic variations, such as the El Niño–Southern Oscillation.
They identified 1,066 regions that experienced periods of too much, or not enough rainfall from 2002 to 2021 with a new algorithm using observations from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellites.
This classified 505 'wet' clusters and 561 'dry' clusters, with an increasing severity of events in the seven years since 2015, which were recognized as among the warmest in history. From 2015 to 2021, the number of 'most extreme' events, among the 30 wettest or driest, increased to four from three per year.
Monday's study noted an increase in the wet-to-dry event ratio from 15° S to 20° N, and a decrease in three areas between 15° N and 50° N, supporting the hypothesis that wet and dry areas are inversely affected by extreme events.
The most intense dry event observed was a record-breaking South American drought from 2015-2016, while the greatest pluvial had been ongoing since 2002 through 2021, affecting most of sub-Saharan Africa above 10° S and leading to flooding and Lake Victoria to rise to its highest levels ever in 2020, inundating homes and infrastructure.
Rodell, the lead author, told the Associated Press (AP): "I was surprised to see how well correlated the global intensity was with global mean temperatures."
Speaking to CNN, he explained: "We thought, well, maybe this is related to global warming, because we do know the past seven or so years have been the hottest on record [...] Sure enough, there was a significant correlation between this total worldwide intensity of these events and the temperature record."
About the study's reliability, he said: "What I feel more confident about is that as the world warms, we’re going to see the greater global intensity of all the wet and dry events increase, meaning they’re going to be more frequent, larger and more severe in total [...] What happens in a regional sense is a little bit more difficult to say with certainty.
"The study is another way for people to recognize that climate change affects everyone [...] It’s not just about the temperature rising on average around the world, it’s the actual weather events that have severe impacts on people that may be increasing in intensity and frequency."